Two Higgs doublets to explain the excesses pp→γγ(750 GeV)pp\rightarrow \gamma\gamma(750\ {\rm GeV}) and h→τ±μ∓h \to \tau^\pm \mu^\mp

The two Higgs doublet model emerges as a minimal scenario in which to address, at the same time, the $\gamma\gamma$ excess at 750 GeV and the lepton flavour violating decay into $\tau^\pm \mu^\mp$ of the 125 GeV Higgs boson. The price to pay is additional matter to enhance the $\gamma\gamma$ rate, and a peculiar pattern for the lepton Yukawa couplings. We add TeV scale vector-like fermions and find parameter space consistent with both excesses, as well as with Higgs and electroweak precision observables.Comment: 15 pages, 1 figure; v2: discussion of tau-->mu gamma added, leading to an additional constraint. v3: references added, figure 1 recovered and figure 2 adde

Predictive factors of scapular notching in patients with reverse shoulder arthroplasty

AbstractIntroductionThe main complication of reverse shoulder arthroplasty is the development of notches in the scapular pillar, which occurs in 44% to 100% of cases. Furthermore the functional score has been shown to be poorer in patients with high-grade notches. Many options have been proposed to reduce this risk. The purpose of this study was to evaluate the predictive factors of the development of scapular notches.Materials and methodsWe retrospectively evaluated 133 shoulders in 121 patients with reverse shoulder arthroplasty. We performed a radiographic assessment of the effect of positioning the glenoid component with inferior overhang of the glenosphere and the glenometaphyseal angle. All patients were reviewed after 2years follow-up, including a clinical assessment based on the Constant score and X-rays to assess the presence of notches.ResultsNineteen complications were reported, and 14 required revision surgery. We excluded patients in whom prosthetic components were changed. The quality of the X-rays was not satisfactory enough to be analyzed in over 15 patients so they were excluded. One hundred five patients were reviewed. At 2years follow-up, 50.4% of shoulders presented with notches. The Constant score was 69.3 points (54–83) in shoulders without notches, and 66.4 points (38–82) in shoulders with notches. The average glenosphere overhang was 3.5mm (−1 – 8mm). Notches were present in 65.5% if it was less than 3mm and 39.6% if it was more than 2mm (P<0. 05). The average glenometaphyseal angle was 27.3° (4–59°), and notches developed in 72.2% if it was more than 28° and 26.5% if it was less than 28° (P<0.05).ConclusionThe position of the metaglene influences the development of notches. The risk decreases if the glenosphere overhangs the glenoid. The degree of adduction of the arm influences the development of notches and can be correlated with the patient's BMI.Level of evidenceLevel IV retrospective study

Is radiographic measurement of distal femoral torsion reliable?

BACKGROUND: Distal femur torsion (DFT) is a crucial parameter in knee replacement surgery. The reference standard for measuring DFT is posterior condylar angle (PCA) measurement using computed tomography (CT). The objective of this study was to assess the feasibility and reliability of a radiographic PCA measurement method. MATERIALS AND METHODS: We studied 125 osteoarthritic knees in 79 patients (42 women and 37 men) with a mean age of 71.6 ± 8.8 years (range 47 to 86 years); 32 knees were aligned, 85 in varus, and eight in valgus. DFT was measured on an antero-posterior (AP) radiograph of the knee in 90° of flexion (known as the seated AP view). The PCA was defined as the angle subtended by the tangent to the posterior condyles and the transepicondylar axis (anatomic PCA [aPCA]) or the line connecting the lateral epicondyle to the medial sulcus (surgical PCA [sPCA]). The PCA was conventionally recorded as positive in the event of external torsion and negative in the event of internal torsion. PCA measurements were performed three times by each of five observers to allow assessments of inter-observer and test-retest reliabilities. RESULTS: aPCA was consistently negative (mean, -6.1 ± 1.6°) (range, 0 to -10°); inter-observer and test-retest reliability were satisfactory (0.54 CONCLUSION: Radiographic measurement of DFT is simple and non-invasive. Measurement reproducibility was satisfactory for aPCA but not for sPCA. aPCA showed marked inter-individual variability and tended to increase when the knee was in valgus. Mean aPCA values were comparable to those reported using CT. In contrast to CT, radiographic DFT measurement can easily be incorporated into the pre- and postoperative work-ups for knee replacement surgery, provided the patient can achieve 90° of knee flexion. LEVEL OF EVIDENCE: Level IV, prospective cohort study

Total ankle arthroplasty - total ankle arthroplasty in Western France: influence of volume on complications and clinical outcome

INTRODUCTION: Total ankle arthroplasty (TAA) has become an alternative to ankle arthrodesis in the treatment of advanced osteoarthritis. "The difficulty of performing a total ankle replacement and the corresponding steep learning curve" has resulted in a proposal "to limit ankle replacement to centers that have performed at least ten total ankle replacements for at least 3 years". The aim of this study was to evaluate the influence of the frequency of TAA procedures on the complications and outcome of these arthroplasties. MATERIALS AND METHODS: This retrospective series included 183 cases who underwent surgery between 1997-2010 in eight centers: three high volume centers performed at least five TAA per year (100 cases) and six low volume centers performed less than five TAA per year (78 cases). RESULTS: The clinical assessment was performed in 133 cases that were reviewed after a mean 39 months ± 29 of follow-up. The preoperative AOFAS score was 33 ± 4 and 77 ± 15 at the final follow-up. The five-year survival rate was 86%. No significant difference was found between the groups for the AOFAS score or implant survival at the final follow-up. The high volume centers experienced more complications (45% versus 13%) but fewer implant failures (8% versus 13%) overall compared to the low volume centers. DISCUSSION: The outcome of TAA depends mainly upon the pertinence of the indication and the associated procedures that may be necessary. Rather than limiting TAA to high volume reference centers, we suggest that the assessment of each case within a predetermined area should be done in a network. This would determine the degree of specialization required for each TAA case and provide all patients with safe and equal access to this therapeutic option. LEVEL OF EVIDENCE: IV - Retrospective study

Two-stage reconstruction of post-traumatic segmental tibia bone loss with nailing

Introduction Treatment of lower extremity segmental bone loss is difficult. Masquelet et al. proposed a two-stage technique: first, debridement and filling of bone loss with an acrylic spacer; second, bone reconstruction by filling with cancellous bone in the space left free (following cement removal) inside the so-called self-induced periosteal membrane. In the originally described technique, the fracture site is stabilized by an external fixator, which remains in place throughout the bone healing process, i.e., often longer than 9 months with all the known disadvantages of this type of assembly. Following the principle of two-stage reconstruction, we modified the technique by reconstructing around an intramedullary-locking nail placed in the first stage. Hypothesis This technique prevents the mechanical complications related to external fixator use and provides faster resumption of weight-bearing. Patients and methods Twelve patients were operated for segmental tibial bone loss greater than 6 cm resulting from injury (four cases) or aseptic necrosis (one case) or septic necrosis (seven cases). All the patients were operated on in an emergency setting and the first stage was performed before the 2nd week. A free muscle flap (ten patients) or a pediculated fasciocutaneous flap (two patients) was necessary during this first step to cover the site and provide good conditions for secondary bone growth. The follow-up was 39.5 months (range, 12–94 months). Results Complete weight-bearing was resumed at a mean 4 months. After the second step, all the patients except one had apparently healed (complete weight-bearing with no pain). Five septic complications occurred after the second step, in one case leading to reconstruction failure. Four other patients had infectious complications successfully treated (as of the last follow-up) either by changing the nail in two cases or by prolonged antibiotic therapy in two other cases, with no graft loss. Discussion The use of the intramedullary nail facilitates the Masquelet technique by allowing the patient to resume weight-bearing more quickly and avoiding secondary fractures. However, the risk of sepsis remains high but can be controlled without compromising the final bone union in four cases out of five. Level of evidence Level IV. Retrospective study

Front Behav Neurosci

Cognitive impairment in Down syndrome (DS) has been linked to increased synaptic inhibition. The underlying mechanisms remain unknown, but memory deficits are rescued in DS mouse models by drugs targeting GABA receptors. Similarly, administration of epigallocatechin gallate (EGCG)-containing extracts rescues cognitive phenotypes in Ts65Dn mice, potentially through GABA pathway. Some developmental and cognitive alterations have been traced to increased expression of the serine-threonine kinase DYRK1A on Hsa21. To better understand excitation/inhibition balance in DS, we investigated the consequences of long-term (1-month) treatment with EGCG-containing extracts in adult mBACtgDyrk1a mice that overexpress Dyrk1a. Administration of POL60 rescued components of GABAergic and glutamatergic pathways in cortex and hippocampus but not cerebellum. An intermediate dose (60 mg/kg) of decaffeinated green tea extract (MGTE) acted on components of both GABAergic and glutamatergic pathways and rescued behavioral deficits as demonstrated on the alternating paradigm, but did not rescue protein level of GABA-synthesizing GAD67. These results indicate that excessive synaptic inhibition in people with DS may be attributable, in large part, to increased DYRK1A dosage. Thus, controlling the level of active DYRK1A is a clear issue for DS therapy. This study also defines a panel of synaptic markers for further characterization of DS treatments in murine models

Searches at HERA for Squarks in R-Parity Violating Supersymmetry

A search for squarks in R-parity violating supersymmetry is performed in e^+p collisions at HERA at a centre of mass energy of 300 GeV, using H1 data corresponding to an integrated luminosity of 37 pb^(-1). The direct production of single squarks of any generation in positron-quark fusion via a Yukawa coupling lambda' is considered, taking into account R-parity violating and conserving decays of the squarks. No significant deviation from the Standard Model expectation is found. The results are interpreted in terms of constraints within the Minimal Supersymmetric Standard Model (MSSM), the constrained MSSM and the minimal Supergravity model, and their sensitivity to the model parameters is studied in detail. For a Yukawa coupling of electromagnetic strength, squark masses below 260 GeV are excluded at 95% confidence level in a large part of the parameter space. For a 100 times smaller coupling strength masses up to 182 GeV are excluded.Comment: 32 pages, 14 figures, 3 table

Forward pi^0 Production and Associated Transverse Energy Flow in Deep-Inelastic Scattering at HERA

Deep-inelastic positron-proton interactions at low values of Bjorken-x down to x \approx 4.10^-5 which give rise to high transverse momentum pi^0 mesons are studied with the H1 experiment at HERA. The inclusive cross section for pi^0 mesons produced at small angles with respect to the proton remnant (the forward region) is presented as a function of the transverse momentum and energy of the pi^0 and of the four-momentum transfer Q^2 and Bjorken-x. Measurements are also presented of the transverse energy flow in events containing a forward pi^0 meson. Hadronic final state calculations based on QCD models implementing different parton evolution schemes are confronted with the data.Comment: 27 pages, 8 figures and 3 table

Deep-Inelastic Inclusive ep Scattering at Low x and a Determination of alpha_s

A precise measurement of the inclusive deep-inelastic e^+p scattering cross section is reported in the kinematic range 1.5<= Q^2 <=150 GeV^2 and 3*10^(-5)<= x <=0.2. The data were recorded with the H1 detector at HERA in 1996 and 1997, and correspond to an integrated luminosity of 20 pb^(-1). The double differential cross section, from which the proton structure function F_2(x,Q^2) and the longitudinal structure function F_L(x,Q^2) are extracted, is measured with typically 1% statistical and 3% systematic uncertainties. The measured partial derivative (dF_2(x,Q^2)/dln Q^2)_x is observed to rise continuously towards small x for fixed Q^2. The cross section data are combined with published H1 measurements at high Q^2 for a next-to-leading order DGLAP QCD analysis.The H1 data determine the gluon momentum distribution in the range 3*10^(-4)<= x <=0.1 to within an experimental accuracy of about 3% for Q^2 =20 GeV^2. A fit of the H1 measurements and the mu p data of the BCDMS collaboration allows the strong coupling constant alpha_s and the gluon distribution to be simultaneously determined. A value of alpha _s(M_Z^2)=0.1150+-0.0017 (exp) +0.0009-0.0005 (model) is obtained in NLO, with an additional theoretical uncertainty of about +-0.005, mainly due to the uncertainty of the renormalisation scale.Comment: 68 pages, 24 figures and 18 table

Measurements of Transverse Energy Flow in Deep-Inelastic Scattering at HERA

Measurements of transverse energy flow are presented for neutral current deep-inelastic scattering events produced in positron-proton collisions at HERA. The kinematic range covers squared momentum transfers Q^2 from 3.2 to 2,200 GeV^2, the Bjorken scaling variable x from 8.10^{-5} to 0.11 and the hadronic mass W from 66 to 233 GeV. The transverse energy flow is measured in the hadronic centre of mass frame and is studied as a function of Q^2, x, W and pseudorapidity. A comparison is made with QCD based models. The behaviour of the mean transverse energy in the central pseudorapidity region and an interval corresponding to the photon fragmentation region are analysed as a function of Q^2 and W.Comment: 26 pages, 8 figures, submitted to Eur. Phys.